Common channel flow control method and system

ABSTRACT

A flow control method includes a step of receiving individual data of each session from a network in an individual trunk apparatus and transmitting the received individual data as a transmission side common channel data to a common buffer, a step of temporarily storing data of plural sessions received from the individual trunk apparatus all at once and monitoring the congestion of the common channel according to the common buffer use amount, and upon detection of a congestion level, a step of stopping or limiting transmission of individual data of a session corresponding to a QoS class having a low priority from the individual trunk apparatus to the common buffer.

TECHNICAL FIELD

This invention relates to a wireless communication system having commonchannels for multiplex transmission of data and individual channels aswireless transmission lines between a base transceiver station andmobile terminals, and particularly to a flow control of a common channelin a base station control system installed in a wireless communicationsystem such as mobile communication.

BACKGROUND ART

In the field of mobile communication systems mainly including portabletelephone systems, the number of users increases rapidly, and alsodiversified content services have increased the amount of transmissiondata. This escalates demands for higher communication qualities.However, since the radio wave resources for communication havelimitation, for example, in the case of communication congestion in aportable telephone system, namely, when a congestion condition occurs ata base transceiver station, problems occurs in communication quality,such as partial interruption of communication.

As countermeasures, various methods have been adopted. One of them caneliminate the congestion condition by flow control of communication datain a base transceiver station transmitting-receiving control system.This method is adopted for flow control of individual data concernedwith common channels particularly in the case that common channels formultiplex transmission of data and individual channels are included asradio wave transmission lines between a base transceiver station andmobile terminals, providing accomplishments in acquiring the requiredcommunication quality.

Hereinbelow, a conventional method of flow control for the commonchannel in a base transceiver station will be described.

FIG. 1 shows a construction of a base station transmitting-receivingcontrol apparatus in wireless communication providing multiple accessincluding common channels for multiplex transmission. Here, it shows adata flow from TCP/IP (transmission control protocol/Internet protocol)network 2 to the base transceiver station (BTS; base transceiverstation) 4 around base station transmitting-receiving control apparatus1 for wireless communication, with assumption of multiple accessincluding common channels for multiplex transmission.

Data for each session is transmitted from TCP/IP network 2 to exchange 3and from exchange 3 via a plurality of individual lines L totransmitting-receiving control apparatus 1 of the base transceiverstation. The data is subjected to necessary processes intransmitting-receiving control apparatus 1 and then transmitted to basetransceiver station 4. Further, while not shown in the drawing, themultiplexed data is transmitted via the base transceiver station tocommunication terminals (remote terminals), which are communicationobjects.

Transmitting-receiving control apparatus 1 comprises individual trunkapparatus 11 receiving individual lines L, common buffer apparatuses 12a, 12 b corresponding to common channels, multiplexing apparatus 13providing connection to base transceiver station 4 with multiplexing aplurality of channels. Within individual trunk apparatus 11, for eachindividual line L, individual line unit “a” for receiving individualdata is provided for each session. In the following description, it isassumed that there are n channels including channel 1 (ch.1) and channel2 (ch.2) for common channels and the remaining channels are forindividual channels, and that common buffer apparatus 12 a correspondsto channel 1 which temporarily stores individual data pieces (a1, a2,a3) from the individual line unit for three lines. Similarly, the commonbuffer apparatus 12 b corresponds to channel 2 that temporarily storesindividual data pieces (a4, a5, a6) from the individual line unit forthree lines. Further, individual channels in multiplexing apparatus 13correspond to individual line unit “a” in the individual trunk apparatus11 one to one, respectively.

Next, the operation and process in transmitting-receiving controlapparatus 1 will be described.

At first, individual trunk apparatus 11 receives individual data foreach session with the individual line unit “a” and transmits to commonbuffer apparatus 12 a the individual data piece (for example, individualdata pieces a1, a2, a3) requiring the multiplexing process. Individualtrunk apparatus 11 transmits individual data corresponding to anindividual channel to multiplexing apparatus 13 as it is.

Common buffer apparatus 12 a temporarily stores these pieces of datatransmitted from individual trunk apparatus 11 and then transmits themto multiplexing apparatus 13. Multiplexing apparatus 13 executes amultiplexing process for the data received from common buffer apparatus12 a and transmits it to base transceiver station 4 as data of commonchannel (ch.1).

Now, the method of flow control will be described for the case that acongestion condition occurs in common channel ch.1. on the basis of FIG.2 in which only individual data pieces of sessions associated with thecommon channel ch.1 are shown for individual trunk apparatus 11.

At first, in S400, individual data for each session is transmitted fromindividual trunk apparatus 11 to common buffer apparatus 12 a. As aresult, an amount of data temporarily stored in common buffer apparatus12 a, namely, an amount of the used portion in the buffer, exceeds acongestion threshold value in step S401. That is, a congestion conditionis detected.

As a result, in step S402, common buffer apparatus 12 a informsindividual trunk apparatus 11 about setting the flow control forindividual data pieces a1, a2, and a3 using a broadcast message. Inresponse to this notice of setting the flow control, the individualtrunk apparatus 11 uniformly stops or restricts transmission ofindividual data pieces a1, a2, and a3 to common buffer apparatus 12 a.

Stopping or restricting the transmission causes the amount of the usedportion of the buffer to decrease below the congestion threshold in stepS403, eliminating the congestion condition in common channel ch.1. Inresponse to this, in step S404, common buffer apparatus 12 a informsindividual trunk apparatus 11 about release of the flow control forindividual data pieces a1, a2, and a3. Then, in step S405, transmissionfrom individual trunk apparatus 11 to common buffer apparatus 12 a isrestored to the usual data flow rate. Here, the data flow rate isrepresented as an amount of data per a unit interval, typically, thenumber of bits of data per a unit interval.

According to the above-described method the congestion condition can beeliminated in common channel ch.1. However, in this method of flowcontrol, because the data rate is uniformly restricted for each session,the required communication quality or performance may not be achieveddue to data delay in accordance with the quality of service (QoS;Quality of service) class required for each session. For example, thoughno problem occurs in communication of a still picture by such a flowcontrol, in a moving picture communication associated with a voice, therequired QoS may not be maintained because a portion of voice or apicture may drop out.

DISCLOSURE OF THE INVENTION

A first object of the present invention is to provide a method of flowcontrol for the common channel capable of eliminating a congestioncondition with a QoS required for each session.

A second object of the present invention is to provide a flow controlsystem for the common channel capable of eliminating a congestioncondition with a QoS required for each session.

The inventor of the present invention was lead to have the presentinvention by directing the inventor's attention to the fact that, inmost cases, a plurality of sessions co-existing in the common channelhave different QoS classes required for respective sessions, andaccompanied with this, limits in restricting data transmission forkeeping necessary communication qualities are different from each other.

That is, the first object of the present invention can be achieved by amethod of flow control for a common channel in a base stationtransmitting-receiving control system for wireless communication formultiple access including the common channel for multiplex transmission,the method comprising the steps of: receiving individual data for eachsession from a network at an individual trunk apparatus and transmittingthe received individual data to the a common buffer as transmission sidecommon channel data; temporarily storing data of a plurality of thesessions received from the individual trunk apparatus in the commonbuffer all together and monitoring a congestion condition of the commonchannel from an amount of used portion of the common buffer; and haltingor restricting transmitting individual data of a session correspondingto a QoS class having a priority that is low to said common buffer fromsaid individual trunk apparatus when the congestion condition isdetected.

According to this method of flow control, congestion conditions can beeliminated with a necessary communication quality because the data flowrate is controlled on the basis of the priority determined on the basisof QoS classes. That is, uniformly, a session with a high priority istransmitted in the same condition as it was transmitted beforerestriction on the data flow rate, and a session with a low priority isrestricted with respect to its data flow rate, so that communicationqualities are kept. Furthermore, if it is confirmed that the congestioncondition has been eliminated, the initial data communication conditioncan be restored by transmitting an instruction of releasing the flowcontrol for restricting the data flow rate from the common buffer sideto the individual trunk apparatus.

In this method, preferably, the session of which data flow rate is to becontrolled is discriminated using the relationship of weighting on thebasis of the data flow rate or an amount of remaining data in the commonbuffer and the QoS class for each session. This controls the data flowrate in the common buffer for each session on the basis of the QoS classrequired for the session with a result that the congestion condition canbe eliminated while the necessary communication quality is maintained.

Further, there are two methods of discriminating the sessioncorresponding to a QoS class with a low priority, and either of them canbe adopted.

(1) When the common buffer receives individual data, its QoS class foreach session is discriminated and registered in advance. When acongestion condition is detected, the common buffer side identifies theobject session from the QoS class to be subjected to the flow controland instructs the individual trunk apparatus to do the flow control withspecifying the individual data corresponding to the session.

(2) When a congestion condition is detected, the common buffer sideinforms the individual trunk apparatus about the object QoS class to besubjected to the flow control. The individual trunk apparatus sideidentifies individual data of the session corresponding to the specifiedQoS class and performs the flow control.

In addition, if a plurality of sessions have the same QoS classes andare to be subjected to the flow control, generally, all sessions aresubjected to the flow control. However, if there is a session from auser requiring a high QoS class, it is also possible to increase thepriority only for the session by setting the above-described thresholdvalue high.

Further, in this invention, the transmission data flow rate from theindividual trunk apparatus may be restricted in accordance with themagnitude of a difference between a value of the priority and athreshold value. This structure more efficiently eliminates congestionconditions with necessary communication qualities. For example, if thedifference between a value of priority and a threshold value is large,an amount of restricting the transmission data flow rate is set large orfull. If the difference is small, the amount of restricting thetransmission data flow rate is set small. That is, the transmission dataflow rate is controlled in proportion to the magnitude of the differencebetween the value of priority and the threshold value to provideefficient elimination of congestion conditions.

The first object of the present invention can be also achieved by amethod of flow control for a common channel in a base stationtransmitting-receiving control system for wireless communication formultiple access including the common channel for multiplex transmission,the method comprising the steps of: receiving individual data for eachsession from a network at an individual trunk apparatus and transmittingthe received individual data to a common buffer as transmission sidecommon channel data; temporarily storing data of a plurality of thesessions received from the individual trunk apparatus in the commonbuffer all together and monitoring a congestion condition of the commonchannel from an amount of used portion of the common buffer; and whenthe congestion condition is detected in the condition that a vacantchannel exists in individual channels on the multiple access, directlyassigning the individual data of the session corresponding to a QoShaving a priority that is high to the vacant channel at a transmissionside from the individual trunk apparatus to transmit it.

This can eliminate congestion conditions with necessary communicationqualities because the data transmission is controlled on the basis ofthe priority determined on the basis of QoS classes. That is, uniformly,a destination of data of a session with a high priority ispreferentially switched from a common channel to a vacant channel in theindividual channels to provide communication qualities and as well aselimination of the congestion condition in the common channel.Furthermore, if it is confirmed that the congestion condition has beeneliminated, the initial data communication condition can be restored bytransmitting from the common buffer side to the individual trunkapparatus an instruction of releasing the data transmission switchingcontrol to a vacant channel in the individual channels.

As switching from a common channel to a vacant channel in individualchannels, there is a concrete example of switching from a common channelto an individual channel on the basis of the specification of the thirdgeneration mobile telecommunications system. In that case, data isdirectly transmitted from an individual channel to the base transceiverstation. In addition, information of a vacant channel in the individualchannels is provided by channel management carried out by callconnection control, and it is checked by either of the common bufferside or the individual trunk apparatus whether such a vacant channelexists on the basis of the information. If existence of a vacant channelis confirmed, the flow control is performed as described above.

Here, preferably, the session of which data transmission is to becontrolled is discriminated using the relationship of weighting on thebasis of the data flow rate or an amount of remaining data in the commonbuffer and the QoS class for each session. This controls the datacommunication for each session on the basis of the QoS class requiredfor the session, so that the congestion condition can be eliminated withnecessary communication quality.

Further, there are two methods of recognizing the session correspondingto a QoS class with a high priority, and either of them can be adopted.

(1) When the common buffer stage receives individual data, its QoS classfor each session is discriminated and registered in advance. When acongestion condition is detected, the common buffer stage identifies theobject session from the QoS class to be subjected to the flow control,specifies the individual data corresponding to the session, and theninstructs the individual trunk apparatus to do the flow control.

(2) When a congestion condition is detected, the common buffer stageinforms the individual trunk stage of the object QoS class to besubjected to the flow control, and the individual trunk stage sideidentifies the individual data of the session corresponding to thespecified QoS class to effect the flow control.

In addition, if a plurality of sessions have the same QoS classes andare objects to be subjected to the switching control, generally, all ofthese sessions are subjected to the switching. However, if there is asession from a user requiring a high QoS class, it is also possible toincrease the priority only for the session by setting theabove-mentioned threshold value low.

In the method of flow control according to the present invention,preferably, an amount of used portion of the common buffer isperiodically monitored at a constant period, and when a congestioncondition is detected, a priority is updated, and it is controlled totransmit from the individual trunk apparatus the individual data of asession of the QoS class corresponding to the priority. This method canprovide a flow control with confirmation of the congestion conditionchanging momentarily in order to enable eliminating congestionconditions efficiently with necessary communication qualities.

The second object of the present invention can be achieved by a flowcontrol system for a common channel in a base stationtransmitting-receiving control system for wireless communication formultiple access including the common channel for multiplex transmission,the system comprising: an individual trunk apparatus for transmittingindividual data for each session received from a network as transmissionside common channel data; and a common buffer apparatus, having a commonbuffer temporarily storing a plurality of the sessions received from theindividual trunk apparatus all together, for monitoring a congestioncondition of the channel from an amount of used portion of the commonbuffer, wherein from the individual trunk apparatus to the common bufferapparatus, transmission of the individual data is halted or restrictedfor a session corresponding to a QoS class having a priority that is lowwhen the congestion condition is detected in said common bufferapparatus.

The second object of the present invention can be also achieved by aflow control system for a common channel in a base stationtransmitting-receiving control system for wireless communication formultiple access including the common channel for multiplex transmission,the system comprising: an individual trunk apparatus for transmittingindividual data for each session received from a network as transmissionside common channel data; and a common buffer apparatus, having a commonbuffer temporarily storing data of a plurality of the sessions receivedfrom the individual trunk apparatus in the common buffer all together,for monitoring a congestion condition of the common channel from anamount of used portion of the common buffer; wherein when the congestioncondition is detected, at the common buffer apparatus, in a conditionthat a vacant channel exists in individual channels on the multipleaccess, the individual trunk apparatus directly assigns the individualdata of the session corresponding to a QoS having a priority that ishigh to the vacant channel at a transmission side to transmit it.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a construction of a base stationtransmitting-receiving control apparatus used in wireless communicationsystem having multiple access including common channels for multiplextransmission.

FIG. 2 is a flow chart illustrating the conventional method of flowcontrol for common channels.

FIG. 3 is a block diagram showing a construction of a common bufferapparatus provided within the base station transmitting-receivingcontrol apparatus in an embodiment of the present invention.

FIG. 4 is a block diagram showing a construction of an individual trunkapparatus provided within the base station transmitting-receivingcontrol apparatus in the embodiment of the present invention.

FIG. 5 is a flow chart generally illustrating the flow control forcommon channels according to a first embodiment of the presentinvention.

FIG. 6 is a flow chart illustrating in detail the process carried out bythe common buffer apparatus in the flow control shown in FIG. 5.

FIG. 7 is a flow chart showing in detail the process carried out bythe-individual trunk apparatus in the flow control shown in FIG. 5.

FIG. 8 is a flow chart generally illustrating the flow control forcommon channels according to a second embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

A first embodiment will be described regarding a method of flow controlfor common channels according to the present invention with reference tothe drawings. The present invention relates to a method of flow controlfor communication channels within base station transmitting-receivingcontrol apparatus 1 in a wireless communication system, with assumptionthat the base station transmitting-receiving control apparatus is formultiple access including common channels for multiplex transmissionlike that shown in FIG. 1. Thus, TCP/IP network 2, exchange 3, basestation transmitting-receiving apparatus 1, and base transceiver station(BTS) 4 are the same as those shown in FIG. 1 in construction andconnection relationships. Particularly, in this embodiment, base stationtransmitting-receiving control apparatus 1 comprises individual trunkapparatus 11 and common buffer apparatuses 12 a and 12 b, andmultiplexing apparatus 13 like that shown in FIG. 1. Here, a pluralityof common buffer apparatuses 12 a and 12 b are represented by commonbuffer apparatus 12 described below.

FIG. 3 shows a construction of common buffer apparatus 12 providedwithin base station transmitting-receiving control apparatus 1 in thefirst embodiment of the present invention. As shown in FIG. 3, commonbuffer apparatus 12 includes:

(1) reception driver 102A for receiving individual data for each sessiontransmitted from individual trunk apparatus 11;

(2) data management unit 121 for obtaining the number of pieces of data,a data flow rate (bit/second) (or an amount of remaining data in thebuffer (the number of bits)) for each QoS class (or session) in commonbuffer 125 on the basis of individual data transmitted from and receivedby common buffer apparatus 12, and for recording them in channelmanagement table 124;

(3) QoS determining unit 122 for managing a parameter and a congestionlevel threshold value for each QoS class (or session) in the channelmanagement table 124 on the basis of QoS class (or a session and QoSclass) of the individual data entering the reception driver 102A;

(4) QoS management unit 123 for storing and managing a parameter whichis set for each QoS class;

(5) channel management table 124 having, for each QoS class (orsession), tables of the number of pieces of data, a data flow rate (orthe number of pieces data remaining the common buffer), a congestionlevel, a congestion level threshold value, a difference between thecongestion level and the congestion level threshold value, and thepresence or the absence of a flow control flag;

(6) common buffer 125 for temporarily storing the received individualdata all together and transmitting it to transmission driver 102B;

(7) flow management unit 126 for monitoring an amount of the usedportion of common buffer 125;

(8) timer management unit 127 for periodically activating flowmanagement unit 126 at a constant interval;

(9) flow control setting/releasing process unit 128 for searching theobject QoS or session to be subjected to or released from the flowcontrol;

(10) flow control setting/releasing format generation unit 129 forgenerating data for informing individual trunk apparatus 11 about theobject QoS or session to be subjected to or released from the flowcontrol or release; and

(11) transmission driver 102B for transmitting individual datatransmitted from common buffer 125 to multiplexing apparatus 13 andtransmitting a flow control setting or releasing instruction data toindividual trunk apparatus 11.

Such a common buffer apparatus 12 is provided in base stationtransmitting-receiving control apparatus 1 in accordance with the numberof channels for multiplex transmission set for multiple access.

On the other hand, FIG. 4 illustrates a structure of individual trunkapparatus 11 provided within base station transmitting-receiving controlapparatus 1 in the first embodiment of the present invention. As shownin FIG. 4, individual trunk apparatus 11 comprises:

(1) reception driver 101A for receiving individual data for each sessionfrom individual line L and receiving flow control setting or releasinginstruction data from common buffer apparatus 12;

(2) individual buffer 113 for temporarily storing the receivedindividual data;

(3) flow setting/releasing process unit 111 for analyzing the flowcontrol setting or releasing instruction data from common bufferapparatus 12;

(4) flow management unit 112 for instructing individual buffer 113 tostop, restrict, or restart a flow of individual data transmission totransmission driver 101 B on the basis of control content (controlsetting or control releasing) informed from flow controlsetting/releasing process unit 111; and

(5) transmission driver 101B for transmitting individual data to commonbuffer apparatus 12 or multiplexing apparatus 13.

Individual buffer 113, flow control setting/releasing process unit 11 1,flow management unit 112 carry out management for each session. Here,only one block is shown in the drawing for each of individual buffer113, flow control setting/releasing process unit 111, and flowmanagement unit 112. In actual, they are prepared in accordance with thenumber of sessions via individual lines L. Individual reception unit “a”shown in FIG. 1, in this embodiment, comprises individual buffer 113,flow control setting/releasing process unit 111, and flow managementunit 112.

Next, there is description about the flow control for the commonchannels in base station transmitting-receiving control apparatus 1including individual trunk apparatus 11 and common buffer apparatus 12as mentioned above. FIG. 5 is a flow chart generally illustrating theprocess for a method of flow control according to this embodiment. Here,it is assumed that communication for each session via individual line Lhas been established and that a certain common channel becomes in acongestion condition.

At first, in step S1, a congestion threshold value is previously setwith respect to an amount of the used portion of common buffer 125.Further, a congestion level threshold value for each QoS class (or eachsession) is set.

Communication starts and it is assumed that in step S2 the amount ofused portion of common buffer 125 exceeds the congestion thresholdvalue. Then, common buffer apparatus 12 identifies the QoS class (orsession) to be subjected to the flow control in step S3 and informsindividual trunk apparatus 11 about a flow control instruction with itscongestion level information. As a result, individual trunk apparatus 11compares the congestion level with a congestion threshold value for eachQoS class in step S3 a and restricts transmitting to common bufferapparatus 12 individual data for each session corresponding to the QoSclass. Here, if session information reaches there, the transmissionrestriction is carried out for the object individual data as it is.

As a result of such a flow control, in step S4, the congestion level ofcommon buffer 125 changes. In response to this change, in step S5,common buffer apparatus 12 newly identifies a QoS class (or session) tobe subjected to the flow control and informs individual trunk apparatus11 about a flow control instruction with its congestion level updatinginformation. In response to this notice, in step S5 a, individual trunkapparatus 11 compares the congestion level updating information with acongestion threshold value for each QoS class and restricts transmittingindividual data to common buffer apparatus 12 for each sessionscorresponding to the QoS class. Here, if the session information reachesthere, transmission restriction is effected for the object individualdata as it is.

As a result of such a flow control, in step S6, the amount of usedportion of common buffer 125 decreases below the congestion thresholdvalue. In response to the decrease in the amount of used portion belowthe congestion threshold value, in step S7, common buffer apparatus 12informs individual trunk apparatus 11 of releasing the flow control. Inresponse to this notice, in step S7 a, individual trunk apparatus 11releases individual data transmission restriction for the session to besubjected to the flow control.

As mentioned above, in this embodiment, the process can eliminate thecongestion conditions while the communication quality corresponding toQoS required for each session is maintained.

Next, the flow of the flow control in common buffer apparatus 12 will bedescribed in detail with reference to FIG. 6.

In step S120, when the reception driver 102A receives individual datafrom individual trunk apparatus 11, or when transmission driver 102Btransmits individual data to multiplexing apparatus 13, data managementunit 121 is activated in step S121. Data management unit 121 detects theQoS class (or session) of the received individual data and incrementsthe number of pieces of data of corresponding QoS class (or session) inchannel management table 124. Further, data management unit 121 obtainsa data flow rate (bit/second) (or an amount of remaining data in thebuffer (the number of bits)) in common buffer 125 from the amount ofdata (the number of bits) of the individual data, and writes the valueon the table of the object QoS class (or session) in channel managementtable 124. Furthermore, data management unit 121 detects the QoS classor session of individual data transmitted from transmission driver 12Band decrements the number of pieces of data of the corresponding QoSclass (or session) in channel management table 124. Further, datamanagement unit 121 subtracts the data flow rate (bit/second) in commonbuffer 125 from the amount of the data (the number of bits) of theindividual data, and writes the value on the table of the object QoSclass (or session) in channel management table 124. In addition, thedata management unit 121 always monitors input and output of individualdata in common buffer apparatus 12 and updates the table of channelmanagement table 124.

Next, in step S122, QoS determining unit 122 is activated. QoSdetermining unit 122 executes the following process.

(1) QoS determining unit 122 recognizes the QoS class (or session andQoS class) of the received individual data, reads a parameter of thecorresponding QoS class from QoS management unit 123, and writes thevalue on a table for the object QoS class (or session) in channelmanagement table 124. The parameter is, for example, such that the QoSclass is classified into five classes, wherein “1” is for a highestpriority quality, and “5” is for a lowest quality, and wherein as aparameter for each QoS class, QoS class 1 (highest priority) is set tohave a multiplying factor of one, which is lowest and QoS class 5(lowest) is set to have a multiplying factor of five, which is highest.Intermediate QoS classes are set to have multiplying factors determinedstepwise.

(2) QoS determining unit 122 sets a congestion level threshold value andwrites it in channel management table 124. The value is a commonthreshold value among all QoS classes (or all sessions). Further, thecongestion level threshold value can be obtained from the number ofsessions existing in common buffer 125 at transmission and receptiontimings of the individual data, the parameter of QoS class for thesession, a quality for the session required from a user, a capacity ofcommon buffer 125, and the like.

In addition, in a usual wireless communication condition, theabove-described multiplying factors are set such that the sessions aresuccessively made an object of the flow control in order from one havinga lower priority level (QoS class 5 (lowest)). However, if sessions withQoS class 1 (highest priority) extremely converge on common channels,and a few of sessions of QoS class 5 (lowest) exist there, in order toeliminate the congestion condition, sessions with QoS class 1 (highestpriority) may become objects of the flow controls.

QoS determining unit 122 also always monitors input and output ofindividual data in common buffer apparatus 12 and updates the tables inchannel management table 124.

After that, in step S123, flow management unit 126 is activated. Flowmanagement unit 126 checks the amount of used portion of common buffer125 (the number of pieces of data stored in the buffer).

Next, in step S124, flow management unit 126 compares the amount of usedportion of common buffer with predetermined congestion threshold valueand determines one among following cases A to C in accordance with thecomparison result to execute a process in accordance with the determinedcase.

Case A:

If the amount of used portion of common buffer exceeds the congestionthreshold value, the determined case is case A. In case A, the flowcontrol is determined to be necessary.

In the process in case A, at first, timer management unit 127 isactivated in step S125. Timer management unit 127 activates a timer tonewly check the amount of the used portion of common buffer 125 byactivating flow management unit 126 at a constant period to execute theprocess from step S123 as long as it is in the condition requiring theflow control.

Next, in step S126, flow control setting/releasing process unit 128 isactivated. Flow control setting/releasing process unit 128 carries outthe following process.

(1) Flow control setting/releasing process unit 128 draws out a dataflow rate (bit/second) (or an amount of buffer remaining data (thenumber of bits)) for each QoS class (or session) from channel managementtable 124.

(2) Flow control setting/releasing process unit 128 calculates acongestion level for each QoS class (or session) by multiplying the dataflow rate (bit/second) (or an amount of buffer remaining data (thenumber of bits)) drawn as mentioned above by the parameter set by QoSdetermining unit 122 in step S122.

(3) Flow control setting/releasing process unit 128 compares thecongestion level obtained in the above-mentioned (2) for each QoS class(or session) with the congestion level threshold value set in thechannel management table 124. Flow control setting/releasing processunit 128 sets a flag indicating necessity of the flow control on a tableof the object QoS class (or session) in channel management table 124 forthe QoS class (or session) of which congestion level exceeds thecongestion threshold value in order to indicate the flow-control object.

(4) Flow control setting/releasing process unit 128 transmits a triggersignal to flow control/releasing format generation unit 128 at the stagein which processing up to the above (3) has been finished.

Next, in response to the trigger signal transmitted in step S126, flowcontrol/releasing format generation unit 128 is activated in step S127.Flow control/releasing format generation unit 128 searches flaginformation in channel management table 124 and reads table informationof QoS class (or session) on which a flag is set and generates data forflow control setting. This data includes the object QoS class (orsession) to be subjected the flow control, the congestion level, thecongestion threshold value, and the like.

After that, in step S128, the flow control setting data generated instep S127 is transmitted as flow control setting instruction informationfrom flow control/releasing format generation unit 128 via transmissiondriver 102B to individual trunk apparatus 11. Then, the process for caseA has finished.

It should be noted that, in the above processing, the congestion levelthreshold value may be set for each QoS class (or session). That is, thedata flow rate (bits/second) (or an amount of remaining data (the numberof bits)) in common buffer 125 for each QoS class (or session) obtainedin step S121 is defined as a congestion level, and at the stage of (2)in step S1 22, a congestion level threshold value is set for each QoSclass (or session). Here, the congestion level threshold value is madecorrespondent to classification (five classes) of QoS class such thatthe congestion level threshold value for QoS class 1 (highest priority)has the highest value and that for QoS class 5 (lowest) has the lowestvalue. Intermediate QoS classes are set to have congestion thresholdvalues determined stepwise. This successively makes an object QoS classto be subjected to the flow control in order from that has the lowpriority (QoS class 5 (lowest)) in accordance with the level ofcongestion.

In addition, in a usual wireless communication condition, the congestionlevel threshold values are set such that the sessions are successivelymade an object of the flow control in order from one having a lowerpriority level (QoS class 5 (lowest)). However, if sessions with QoSclass 1 (highest priority) extremely converge on a common channel, and afew of sessions of QoS class 5 (lowest) exist, in order to eliminate thecongestion condition, sessions with QoS class 1 (highest priority) maybecome objects of the flow controls.

Case B:

In step S124, if the amount of the used portion of the buffer decreasesbelow a flow releasing threshold value after execution of the flowcontrol, it is determined as case B. In case B, the flow control isdetermined to be unnecessary.

In case B, at first, in step S129, the timer management unit 127 isactivated. The timer management unit 127 stops the timer.

Next, in step S12 a, flow control setting/releasing process unit 128 isactivated. Flow control setting/releasing process unit 128 executes thefollowing process.

(1) Flow control setting/releasing process unit 128 resets all flags inchannel management table 124 indicating necessity of the flow controland indicates flow control releasing.

(2) Flow control setting/releasing process unit 128, after process ofabove (1), transmits a trigger signal to flow control/release formatgeneration unit 128.

After that, in step S12 b, in response to the trigger signal generatedin step S12 a, flow control/releasing format generation unit 128 isactivated. Flow control/releasing format generation unit 128 searcheschannel management table 124 for flag information and generates data forinforming of flow control release by confirming that no flag exists.

Next, in step S12 c the flow control releasing data generated in stepS12 b is transmitted as flow control releasing instruction informationfrom flow control/releasing formation generation unit 128 viatransmission driver 102B to individual trunk apparatus 11. Then, theprocess in case B has finished.

Case C:

In step S124, if the comparison result between the amount of usedportion of common buffer and the congestion threshold value indicates anabnormal value, processing proceeds to end of process without executionof these processes.

As mentioned above, processes for cases A, B, and C determined in stepS124 have been described. Furthermore, in the above-mentioneddescription, in the case of A, as long as the amount of buffer usedportion exceeds the congestion threshold value, the congestion conditionwas checked periodically, and the flow control condition was updated inaccordance with the condition. However, if the amount of buffer usedportion exceeds the congestion threshold value, it is also possible tocontinue a constant flow control without updating the flow controlcondition without reserve with assumption that the congestion levelcorresponds to case C until the congestion level decreases to a certainconstant level.

A flow of the flow control in individual trunk apparatus 11 will befurther described in detail with reference to FIG. 7.

At first, the process in the case that the flow control instructioninformation is received from common buffer apparatus 12 will bedescribed.

When the flow control instruction information is received from commonbuffer apparatus 12 in step S1 10, at first, flow controlsetting/releasing process unit 111 is activated in step S111. Flowcontrol setting/releasing process unit 111 executes the followingprocess on the basis of the flow control instruction information fromcommon buffer apparatus 12.

(1) Flow control setting/releasing process unit 111 specifies a QoSclass (or session) to be subjected to the flow control.

(2) Flow control setting/releasing process unit 111 compares thecongestion level of the object QoS class (or session) with thecongestion level threshold value and determines an amount oftransmission data per a unit time interval.

(3) Flow control setting/releasing process unit 111 informs flowmanagement unit 112 about, as control instruction information, the QoSclass (or session) specified as mentioned above and the amount oftransmission data per a unit time interval determined as mentionedabove.

Next, in step S112, flow management unit 112 is activated. Flowmanagement unit 112 sets an amount of transmission data per a unit timeinterval for each session on the basis of the amount of transmissiondata per a unit time interval for QoS class instructed from flow controlsetting/releasing process unit 111 and performs the flow control forindividual data on the basis of the setting value. In addition, whenthere is a notice of the amount of transmission data per a unit timeinterval for each session from flow control setting/releasing processunit 111, the noticed value is used as it is to effect the flowrestriction of individual data. Here, if the level of congestion isconsiderable, the flow restriction to make the amount of transmissiondata zero, namely, stop of transmission, may be possible.

It should be noted that, the process for determining the amount oftransmission data per a unit time interval in step 111 may be previouslydone on the side of common buffer apparatus 12. That is, in commonbuffer apparatus 12, after the process (3) in step 126 shown in FIG. 6,it is also possible by successively executing: calculation for comparing(subtraction) the congestion level with the congestion threshold valueof the QoS class (or session) to be subjected to the flow control; aprocess for writing the difference value on the object QoS class tablein channel management table 124; and transmission of the calculationresult to individual trunk apparatus 11.

Next, the operation of individual trunk apparatus 11 will be describedin the case that flow control release information is received fromcommon buffer apparatus 12.

When the flow control release information is received in step S10, theflow control setting/releasing process unit 111 is first activated instep S111. Flow control setting/releasing process unit 111 specifies aQoS class (or session) to be subjected to the flow control releasing onthe basis of the flow control releasing instruction information fromcommon buffer apparatus 12 and notices the flow management unit 112.

After that, in step S112, the flow management unit 112 is activated.Flow management unit 112 releases the flow control for all sessionscorresponding to the QoS classes instructed from flow controlsetting/releasing process unit 111. Further, when there is a notice ofsession from flow control setting/releasing process unit 111, flowmanagement unit 112 releases the flow control for the session.

As described above, the flow control for common channels according thepresent embodiment is done. According to the first embodiment, becausethe data flow rate is controlled on the basis of the priory determinedon the basis of the QoS class, congestion conditions can be eliminatedwhile the necessary communication quality is maintained. That is,uniformly, the session with a higher priority is communicated in thesame condition as is done before the data flow rate is restricted, andthe session with a low priority is subjected to the data flow raterestriction to maintain the communication quality. Furthermore, becausesessions to be subjected to the data flow rate control is discriminatedusing the relationship of weighting on the basis of the data flow rateor the amount of the remaining data in the common buffer for eachsession and the QoS class, the data flow rate for each session in thecommon buffer is controlled on the basis of the QoS class required forthe session, and congestion conditions can be eliminated with necessarycommunication qualities. In addition, because the transmission data flowrate from the individual trunk stage is restricted in accordance withthe magnitude of a difference between the value of priority and thethreshold value, elimination of congestion conditions can be moreefficiently provided with necessary communication qualities. Forexample, if the difference between the value of a priority and athreshold value is large, the amount for restriction the transmissiondata flow rate is made large or full, and if the difference is small theamount of restriction for the transmission data flow rate is made small.That is, the transmission data flow rate is controlled in proportionwith the magnitude of the difference between the value of the priorityand the threshold value to provide efficient elimination of congestionconditions.

Furthermore, the amount of used portion of the common buffer ismonitored periodically. When a congestion condition is detected, apriority is updated and set, and the transmission of individual data ofa session of a QoS class corresponding to the priority from individualtrunk apparatus is controlled. Accordingly, the flow control can beprovided with confirming the congestion condition changing successively,so that an efficient elimination of congestion conditions is providedwith necessary communication quality.

Now, a second embodiment of a method of common channel flow controlaccording to the present invention will be described with reference todrawings. Here, it is assumed that the construction shown in FIG. 1 isused as the wireless communication system. Particularly, it is assumedthat the structure of the common channel apparatus and an individualtrunk apparatus, respectively shown in FIGS. 3 and 4, are used. Inaddition, as clearly understood from the following operationdescription, this embodiment is different from the first embodiment inthe process of the flow control for common channel using the commonchannel apparatus and individual trunk apparatus.

FIG. 8 generally illustrates a flow of the flow control for commonchannels according to the second embodiment. Here, it is assumed that inthe communication system shown in FIG. 1, communication via anindividual line L for each session has been established and that the nthchannel ch.n which is an individual channel is a vacant channel.

At first, in step S201, the congestion threshold value for the amount ofused portion of common buffer 125 is previously set. Further, acongestion level threshold value of each QoS class (or each session) isset.

In step S202, it is assumed that the amount of used portion of commonbuffer 125 exceeds the congestion threshold value. Then, in step S203,communication buffer apparatus 12 specifies an object QoS class (orsession) to be subjected to the flow control and informs individualtrunk apparatus 11 of the flow control instruction. Further, in stepS203 a, common buffer apparatus 12 switches the destination ofindividual data for each session corresponding to the QoS class to besubjected to the flow control to the vacant channel ch.n of theindividual channels in multiplexing apparatus 13, and performstransmission. Here, if the session information reaches there, the objectindividual data is transmitted after channel is switched to the vacantchannel ch.n.

The transmission with switching to the vacant channel of individualchannels changes the congestion level of common buffer 125 in step S204.Then, in step S205, common buffer apparatus 12 newly specifies a QoSclass (or session) to be subjected to the flow control and informsindividual trunk apparatus 11 of the flow control instruction.

Individual trunk apparatus 11 informed of the new flow controlinstruction performs transmission after destination of individual datafor each session corresponding to the QoS class to be subjected to theflow control is switched to the vacant channel ch.n of individualchannels in the multiplexing apparatus 13 in step S205 a. Here, if thesession information reaches there, the object individual data istransmitted as it is with switching to the vacant channel ch.n.

This flow control decreases the amount of used portion of common buffer125 below the congestion threshold value in step S206. As a result, instep S207, common buffer apparatus 12 informs individual trunk apparatus11 of release of the flow control.

Individual trunk apparatus 11 informed of release of the flow controlreleases the destination switching for individual data of the session tobe subjected to the flow control instep S207 a. That is, the destinationof individual data of these sessions is restored to the original commonbuffer apparatus 12.

In this embodiment, the session with a higher priority on the commonchannel in a congestion condition, namely, the session whose requiredQoS is high, is switched to a vacant channel of individual channels tomaintain the communication quality. In addition, the congestioncondition in the common channel can be also eliminated.

As mentioned above, in the second embodiment, the internal structures ofcommon buffer apparatus 12 and individual trunk apparatus 11 are thesame as those in the first embodiment, and the operation content arealso the same as that of the first embodiment basically. However, thereis a difference such that the parameter or the congestion levelthreshold value is set for each QoS class to specify a session with alow priority in the first embodiment, but to specify a session with ahigh priority in the second embodiment.

Concretely, against the flow of the flow control in common buffer 12according to the first embodiment, QoS determining unit 122 executes thefollowing process at the stage of step S122.

(1) QoS determining unit 122 recognizes the QoS class (or session andthe QoS class) of the received individual data, reads the parameter ofthe corresponding QoS class from QoS management unit 123, and writes thevalue on the table for the object QoS class (or session) in channelmanagement table 124. The parameter is, for example, such that the QoSclass is classified into five classes, wherein “1” is for the highestpriority quality and “5” is for the lowest priority quality, and whereinas a parameter for each QoS class, QoS class 1 (highest priority) is setto have a multiplying factor of five, which is highest, and QoS class 5(lowest) is set to have a multiplying factor of one, which is lowest.Intermediate QoS classes are set to have multiplying factors determinedstepwise.

(2) QoS determining unit 122 sets a congestion level threshold value andwrites the congestion level threshold value in channel management table124. The value is a common threshold value among all QoS classes (or allsession).

Alternatively, the congestion level threshold value is set for each QoSclass (or each session), and thus, QoS determining unit 122 defines thedata flow rate (bit/second) (or the amount of buffer remaining data (thenumber of bits)) in common buffer 125 for each QoS class obtained instep S121 as the congestion level and sets the congestion levelthreshold value for each QoS class (or each session) on the basis of theprocess (2) in step S122 of the first embodiment. During this, thecongestion level threshold value is set to have correspondence withclasses (five classes) of the QoS class such that the QoS class 1(highest priority) is set to have the lowest value of the congestionlevel threshold value and the QoS class 5 (lowest priority) is set tohave the highest value of the congestion level threshold value.Intermediate QoS classes are set to have congestion level thresholdvalues determined stepwise.

The above-mentioned setting enables discrimination of a high QoS class,and thus QoS classes can be successively included in the object of theflow control (transmission with switching to a vacant channel ofindividual channels) in order of priority from high (QoS class 1(highest priority)) in accordance with the congestion level.

As mentioned above, because the second embodiment is different from thefirst embodiment in the process in common buffer apparatus 12, the flowof the flow control in individual trunk apparatus 11 in the secondembodiment is changed from the flow in the first embodiment shown inFIG. 7 as follows:

First, the operation will be described in the case that the flow controlinstruction information is received from common buffer apparatus 12.

In this case, the flow control setting/releasing process unit 111 isactivated in step S111 in FIG. 7. In this embodiment, the flow controlsetting/releasing process unit 111 executes the following process on thebasis of the flow control instruction information from common bufferapparatus 12.

(1) Flow control setting/releasing process unit 111 specifies a QoSclass (or session) to be subjected to the flow control.

(2) Flow management unit 112 is informed of the specified QoS class (orsession) as control instruction information.

Furthermore, in step S112 in FIG. 7, flow management unit 112 isactivated. In this embodiment, flow management unit 112 executes thefollowing process.

(1) From the vacant channel information (the number of vacant channels,object channels) of the individual channels and the session informationcorresponding to the object QoS class instructed from flow controlsetting/releasing process unit 111, flow management unit 112 makes QoSclasses included in the flow control object up to such a QoS class thatthe total number of sessions accumulated from a QoS class having ahigher priority is not larger than the number of the vacant channels inthe individual channels. Here, if the session information from flowcontrol setting/releasing process unit 111 reaches there, the flowmanagement unit 112 makes sessions included in the flow control objectup to such a session that the total number of sessions accumulated froma session having a higher priority is not larger than the number of thevacant channels in the individual channels.

(2) Flow management unit 112 changes a destination of session ofindividual data corresponding to the QoS class of the flow controlobject (or sessions of the flow control object) to the vacant channelch.n of individual channels in multiplexing process apparatus 13. On thebasis of this setting, transmission driver 101B transmits the objectindividual data to the vacant channel ch.n in the multiplexing processapparatus 13.

Next, the process for the case that the flow control release informationis received from common buffer apparatus 12 will be described.

In this case, in step S111 in FIG. 7, the flow control setting/releasingprocess unit 111 is activated. In this embodiment, flow controlsetting/releasing process unit 111 specifies the QoS class (or session)of the flow control release object on the basis of the flow controlrelease instruction information from common buffer apparatus 12 andinforms the flow management unit 112 of it.

Further, in step S112 in FIG. 7, flow management unit 112 is activated.In this embodiment, flow management unit 112 releases the switchedtransmission with vacant channels for all sessions corresponding to theQoS class instructed from flow control setting/releasing process unit111 and they are restored to the original common channels. If there is anotice of a session from flow control setting/releasing process unit111, the session is restored to the common channel.

For switching from the common channel to a vacant channel of individualchannels, as a concrete example, there is proposed switching from acommon channel to an individual channel on the basis of thespecification of the third generation mobile telecommunications. By sucha switching, data is directly transmitted from an individual channel tothe base transceiver station.

Further, the vacant channel information in the individual channels issupplied from the channel management performed in call connectioncontrol. Either of the common buffer apparatus or the individual trunkapparatus checks whether there is a vacant channel on the basis of theinformation. When it is confirmed that there is a vacant channel, theflow control mentioned above according to the second embodiment iscarried out.

In the present invention, the above-mentioned flow control according tothe first embodiment may be used together with the flow controlaccording to the second embodiment. That is, when there is a vacantchannel of individual channels on multiple access in a congestioncondition in the common channel, a portion of sessions in the commonchannel with high priority is switched to vacant channels fortransmission by application of the flow control according to the secondembodiment, and as well as the flow control is executed for individualtransmission of sessions with low priority in common channel byapplication of the first embodiment. This can eliminate congestionconditions with communication quality of each session maintained.

According to the second embodiment, because data transmission iscontrolled on the basis of the priority determined on the basis of theQoS class, congestion conditions can be eliminated with necessarycommunication qualities maintained. That is, uniformly, a destination ofdata of a session with a high priority is preferentially switched from acommon channel to a vacant channel out of individual channels to providecommunication qualities and as well as elimination of the congestioncondition in the common channel. Further, the session of which datatransmission is to be controlled is discriminated using the relationshipof weighting on the basis of the data flow rate or an amount ofremaining data in the common buffer and the QoS class for each session.This controls the data communication for each session on the basis ofthe QoS class required for the session, so that the congestion conditioncan be eliminated with necessary communication quality.

In addition, in the second embodiment, the amount of used portion of thecommon buffer is monitored periodically. When a congestion condition isdetected, a priority is updated and set, and the transmission ofindividual data of a session of a QoS class corresponding to thepriority from individual trunk apparatus is controlled. Accordingly, theflow control can be provided with confirming the congestion conditionchanging momentarily, so that an efficient elimination of congestionconditions is provided with necessary communication quality.

Industrial Applicability

According to the present invention, it is possible to eliminatecongestion conditions with necessary communication quality maintainedbecause the data flow rate is controlled on the basis of the prioritiesdetermined on the basis of QoS classes.

1. A method of flow control for a common channel in a base stationtransmitting-receiving control system for wireless communication formultiple access including said common channel for multiplextransmission, said method comprising the steps of: receiving individualdata for a respective session from a network at a respective individualtrunk apparatus; transmitting the received individual data from saidindividual trunk apparatus to a common buffer as a destination for saidindividual data, said individual data having a priority; temporarilystoring data of a plurality of the sessions received from saidindividual trunk apparatus in said common buffer all together andmonitoring a congestion condition of said common channel from an amountof used portion of said common buffer; and one of halting andrestricting transmitting individual data of a session corresponding to aquality of service (QoS) class having a priority that is low to saidcommon buffer from said individual trunk apparatus, wherein at least oneof the step of receiving individual data and the step of temporarilystoring said data to the common buffer includes vacant channeldetermination for determining whether a vacant channel exists on saidmultiple access, the method further comprising the steps of, when saidcongestion condition is detected in a condition that the vacant channelexists in individual channels on said multiple access, directlyassigning individual data of the session corresponding to a QoS having apriority that is high to said vacant channel at a transmission side fromthe individual trunk apparatus to transmit it, wherein, when saidcongestion condition is eliminated, the flow control of halting orrestricting transmission of the individual data of the session of theQoS class of the low priority is released and the transmission of theindividual data of the QoS class of the high priority is switched to thecommon channel from the vacant channel, wherein an amount of usedportion of said common buffer is periodically monitored at a constantperiod, and when said congestion condition is detected, said priority isupdated, and transmitting from said individual trunk apparatus theindividual data of a session of the QoS class corresponding to thepriority is controlled, wherein said priority is set as a value obtainedby multiplying one of a data flow rate and an amount of remaining datain the common buffer for each QoS class by a predetermined multiplyingfactor corresponding to the QoS class, wherein a multiplying factor fora class with a high QoS is set low, and a multiplying factor for a classwith a low QoS is set high, and wherein any of QoS classes of which avalue of said priority exceeds a predetermined threshold value isdefined as said QoS class having said priority that is low.
 2. Themethod of flow control according to claim 1, wherein a transmission dataflow rate from said individual trunk apparatus to said common buffer iscontrolled for the session corresponding to the QoS class to becontrolled on a basis of a magnitude of a difference between a value ofsaid priority and said threshold value.
 3. The method of flow controlaccording to claim 2, wherein an amount of used portion of said commonbuffer is periodically monitored at a constant period, and when acongestion condition is detected, said priority is updated, andtransmitting from said individual trunk apparatus the individual data ofa session of the QoS class corresponding to the priority is controlled.4. A method of flow control for a common channel in a base stationtransmitting-receiving control system for wireless communication formultiple access including said common channel for multiplextransmission, said method comprising the steps of: receiving individualdata for a respective session from a network at a respective individualtrunk apparatus; transmitting the received individual data from saidindividual trunk apparatus to a common buffer as a destination for saidindividual data, said individual data having a priority; temporarilystoring data of a plurality of the sessions received from saidindividual trunk apparatus in said common buffer all together andmonitoring a congestion condition of said common channel from an amountof used portion of said common buffer; and one of halting andrestricting transmitting individual data of a session corresponding to aquality of service (QoS) class having a priority that is low to saidcommon buffer from said individual trunk apparatus, wherein at least oneof the step of receiving individual data and the step of temporarilystoring said data to the common buffer includes vacant channeldetermination for determining whether a vacant channel exists on saidmultiple access, the method further comprising the steps of, when saidcongestion condition is detected in a condition that the vacant channelexists in individual channels on said multiple access, directlyassigning individual data of the session corresponding to a QoS having apriority that is high to said vacant channel at a transmission side fromthe individual trunk apparatus to transmit it, wherein, when saidcongestion condition is eliminated, the flow control of halting orrestricting transmission of the individual data of the session of theQoS class of the low priority is released and the transmission of theindividual data of the QoS class of the high priority is switched to thecommon channel from the vacant channel, wherein an amount of usedportion of said common buffer is periodically monitored at a constantperiod, and when said congestion condition is detected, said priority isupdated, and transmitting from said individual trunk apparatus theindividual data of a session of the QoS class corresponding to thepriority is controlled, wherein said priority is set as a data flow ratein the common buffer for each QoS class, wherein a threshold value ispredetermined for each QoS class such that a threshold value for a highQoS class is set high and a threshold value for a low QoS class is setlow, and wherein a QoS class of which said value of priority exceeds thethreshold value of the corresponding QoS class is defined as said QoSclass having said priority that is low.
 5. A flow control system for acommon channel in a base station transmitting-receiving control systemfor wireless communication for multiple access including said commonchannel for multiplex transmission, said system comprising: anindividual trunk apparatus transmitting individual data for each sessionreceived from a network to a common buffer as a destination for saidindividual data; and a common buffer apparatus, having said commonbuffer temporarily storing data of a plurality of the sessions receivedfrom said individual trunk apparatus all together, and monitoring acongestion condition of the channel from an amount of a used portion ofsaid common buffer; and wherein said individual data has a transmissionpriority, wherein, from said individual trunk apparatus to said commonbuffer apparatus, transmission of the individual data is one of haltedand restricted for a session corresponding to a QoS class having apriority that is low when a congestion condition is detected in saidcommon buffer apparatus, wherein, when said congestion condition isdetected in a condition that the vacant channel exists in individualchannels on said multiple access, directly assigning individual data ofthe session corresponding to a QoS having a priority that is high tosaid vacant channel at a transmission side from the individual trunkapparatus to transmit it wherein, when said congestion condition isdetected on said common buffer apparatus, in a condition that the vacantchannel exists in individual channels on said multiple access, saidindividual trunk apparatus directly assigns the individual data of thesession corresponding to a QoS having a priority that is high to saidvacant channel at a transmission side to transmit it, wherein, when saidcongestion condition is eliminated, the flow control of halting orrestricting transmission of the individual data of the session of theQoS class of the low priority is released and the transmission of theindividual data of the QoS class of the high priority is switched to thecommon channel from the vacant channel, wherein an amount of usedportion of said common buffer is periodically monitored at a constantperiod, and when said congestion condition is detected, said priority isupdated, and transmitting from said individual trunk apparatus theindividual data of a session of the QoS class corresponding to thepriority is controlled, wherein said priority is set as a value obtainedby multiplying one of a data flow rate and an amount of remaining datain the common buffer for each QoS class by a predetermined multiplyingfactor corresponding to the QoS class, wherein the multiplying factorfor a class with a high QoS is set low, and the multiplying factor for aclass with a low QoS is set high, and wherein any of the QoS classes forwhich a value of said priority exceeds a predetermined threshold isdefined as said QoS class having said priority that is low.
 6. The flowcontrol system according to claim 5, wherein an amount of used portionof said common buffer is periodically monitored at a constant period,and when a congestion condition is detected, said priority is updated,and transmitting from said individual trunk apparatus the individualdata of a session of the QoS class corresponding to the priority iscontrolled.
 7. The flow control system according to claim 5, whereinsaid common buffer apparatus further comprises: a reception driver forreceiving the individual data for each session transmitted from saidindividual trunk apparatus; a channel management table having a tablerepresenting, for each QoS class, the number of pieces of data, a dataflow rate, a congestion level, a congestion level threshold value, adifference between the congestion level and the congestion levelthreshold value, and the presence or absence of a flow control flag; adata management unit obtaining, for each QoS class in said commonbuffer, the number of pieces of data and the data flow rate (bit/second)on the basis of the individual data transmitted to and received fromsaid common buffer apparatus and for recording them in said channelmanagement table; a QoS determining unit for managing a parameter andthe congestion level threshold value on a table for each QoS class insaid channel management table on a basis of the QoS class of theindividual data entering said reception driver; a QoS management unitfor storing and managing a parameter which is set for each said QoSclass; a flow management unit for monitoring an amount of used portionof said common buffer; a timer management unit for periodicallyactivating said flow management unit at said constant period; a flowcontrol setting/releasing process unit for searching an object QoS classto be subjected to the flow control or to be released; a flow controlsetting/releasing format generation unit for generating data forinforming said individual trunk apparatus of the object QoS class to besubjected to the flow control or to be released; and a transmissiondriver for transmitting the individual data transmitted from said commonbuffer to a multiplexing apparatus and transmitting flow control settingor releasing instruction data to said individual trunk apparatus.
 8. Theflow control system according to claim 7, wherein said individual trunkapparatus comprises: a reception driver for receiving individual datafor each session from an individual line and receiving flow controlsetting or releasing instruction data from said common buffer apparatus;an individual buffer for temporarily storing the received individualdata; a flow control setting/releasing process unit for analyzing saidflow control setting or releasing instruction data; a transmissiondriver for transmitting said individual data to said common bufferapparatus; and a flow management unit for instructing said individualbuffer to one of halt, restrict, and re-start the flow of transmittingthe individual data corresponding to the QoS class of the low priorityto said transmission driver, and to switch transmission of theindividual data corresponding to the QoS class of the high priority tothe vacant channel, on a basis of the control content informed from saidflow control setting/releasing process unit.
 9. A flow control systemfor a common channel in a base station transmitting-receiving controlsystem for wireless communication for multiple access including saidcommon channel for multiplex transmission, said system comprising: anindividual trunk apparatus transmitting individual data for each sessionreceived from a network to a common buffer as a destination for saidindividual data; and a common buffer apparatus, having said commonbuffer temporarily storing data of a plurality of the sessions receivedfrom said individual trunk apparatus in said common buffer all together,and monitoring a congestion condition of said common channel from anamount of a used portion of said common buffer; and wherein saidindividual data has a transmission priority, wherein, when saidcongestion condition is detected on said common buffer apparatus, in acondition that a vacant channel exists in individual channels on saidmultiple access, said individual trunk apparatus directly assigns theindividual data of the session corresponding to a QoS having a prioritythat is high to said vacant channel at a transmission side to transmitit, wherein, when said congestion condition is eliminated, the flowcontrol of halting or restricting transmission of the individual data ofthe session of a QoS class of the low priority is released and thetransmission of the individual data of the QoS class of the highpriority is switched to the common channel from the vacant channel,wherein an amount of used portion of said common buffer is periodicallymonitored at a constant period, and when said congestion condition isdetected, said priority is updated, and transmitting from saidindividual trunk apparatus the individual data of a session of the QoSclass corresponding to the priority is controlled, wherein said priorityis set as a data flow rate in the common buffer for each QoS class,wherein a threshold value is predetermined for each QoS class such thata threshold value for a high QoS class is set high and a threshold valuefor a low QoS class is set low, and wherein a QoS classes of which saidvalue of priority exceeds the threshold value of the corresponding QoSclass is defined as said QoS class having said priority that is low. 10.The flow control system according to claim 9, wherein an amount of usedportion of said common buffer is periodically monitored at a constantperiod, and when a congestion condition is detected, said priority isupdated, and transmitting from said individual trunk apparatus theindividual data of a session of the QoS class corresponding to thepriority is controlled.
 11. The flow control system according to claim9, wherein said common buffer apparatus further comprises: a receptiondriver for receiving the individual data for each session transmittedfrom said individual trunk apparatus; a channel management table havinga table representing, for each QoS class, the number of pieces of data,a data flow rate, a congestion level, a congestion level thresholdvalue, a difference between the congestion level and the congestionlevel threshold value, and the presence or absence of a flow controlflag; a data management unit obtaining, for each QoS class in saidcommon buffer, the number of pieces of data and the data flow rate(bit/second) on the basis of the individual data transmitted to andreceived from said common buffer apparatus and for recording them insaid channel management table; a QoS determining unit for managing aparameter and the congetion level threshold value on a table for eachQoS class in said channel management table on a basis of the QoS classof the individual data entering said reception driver; a QoS managementunit for storing and managing a parameter which is set for each said QoSclass; a flow management unit for monitoring an amount of used portionof said common buffer; a timer management unit for periodicallyactivating said flow management unit at said constant period; a flowcontrol setting/releasing process unit for searching an object QoS classto be subjected to the flow control or to be released; a flow controlsetting/releasing format generation unit for generating data forinforming said individual trunk apparatus of the object QoS class to besubjected to the flow control or to be released; and a transmissiondriver for transmitting the individual data transmitted from said commonbuffer to a multiplexing apparatus and transmitting flow control settingor releasing instruction data to said individual trunk apparatus. 12.The flow control system according to claim 11, wherein said individualtrunk apparatus comprises: a reception driver for receiving individualdata for each session from an individual line and receiving flow controlsetting or releasing instruction data from said common buffer apparatus;an individual buffer for temporarily storing the received individualdata; a flow control setting/releasing process unit for analyzing saidflow control setting or releasing instruction data; a transmissiondriver for transmitting said individual data to said common bufferapparatus; and a flow management unit for instructing said individualbuffer to one of halt, restrict, and re-start the flow of transmittingthe individual data corresponding to the QoS class of the low priorityto said transmission driver, and to switch transmission of theindividual data corresponding to the QoS class of the high priority tothe vacant channel, on a basis of the control content informed from saidflow control setting/releasing process unit.